扩展基础冲剪承载力设计可靠性分析

Reliability analysis of shear capacity of RC spread foundations

扩展基础的基底压力分布一般呈非线性特征。扩展基础设计时,为简化设计,将基底反力按线性分布计算。通过一组试验对基底反力按线性分布简化计算的扩展基础冲剪承载力设计的可靠性进行评价。试验结果表明:扩展基础的抗冲剪承载力在基底反力按线性分布简化计算时,其抗剪验算结果能够满足构件可靠度设计指标要求;在偏心荷载作用下,扩展基础冲剪承载力可靠性指标大于其在中心荷载作用下的可靠性指标。扩展基础设计可靠性受诸多因素影响,如构件试验未考虑结构荷载传递计算模式不确定性的影响,钢筋对冲剪承载力的影响等,且可靠性设计的深入研究需要一定数量的试验样本进行统计分析,该问题还需要进一步深入研究。

Contact pressure beneath spread foundation generally presents nonlinear character. For simplified design,contact pressure is calculated usually by linear distribution in design of spread foundations. Through a set of experimental models,the reliability of shear capacity calculated by linear distribution in contact pressure of spread foundations was evaluated. The results show that the results of shear checking may meet for the requirement of reliability indexes when the shear capacity calculated by linear distribution in contact pressure. The reliability indexes of shear capacity of spread foundations under eccentric load are greater than which under centric load. The reliability of spread foundations was effected by many factors. For example,the effect of loads transfer and calculation modes in uncertainty was not considered in member experiments,the effect of reinforcement on shear capacity,etc. In addition,the further study of reliability design need more experimental samples for statistics and analysis. So the problem needs further research.